Society of Nuclear Medicine Procedure Guideline for Parathyroid Scintigraphy

Primary hyperparathyroidism is characterized by increased synthesis and release of parathyroid hormone, which produces an elevated serum calcium level and a decline in serum inorganic phosphates. Asymptomatic patients are frequently diagnosed due to screening by automatic multi-chemistry panels. The vast majority of cases of primary hyperparathyroidism (80–85%) are due to single or multiple hyperfunctioning adenomas. Hyperplasia of several or all parathyroid glands accounts for approximately 12–15% of cases, while parathyroid carcinomas occur in only 1–3% of cases of hyperparathyroidism. In general, parathyroid adenomas larger than 500 mg can be detected scintigraphically. Recently, Tc-99m sestamibi has allowed detection of hyperplastic glands, although with less sensitivity than adenomas. Dual phase or double phase imaging refers to utilizing Tc-99m sestamibi and acquiring early and delayed images. Dual isotope or subtraction studies refer to protocols using two different radiopharmaceuticals for imaging acquisition.